Aluminum nitride-based filler, and resin composition

Abstract

The present invention provides: an aluminum nitride-based filler having excellent water resistance and thermal conductivity; and a resin composition having excellent water resistance and thermal conductivity. This aluminum nitride-based filler contains fibrous aluminum nitride particles having an oxide film formed on the surface thereof, with the oxide film on the aluminum nitride particles being surface treated with a phosphorus compound, and is characterized in that the surface oxygen amount, as measured using an NDIR method, is 1.98-9.40%, and if the specific surface area of the aluminum nitride particles, as measured using a BET method, is denoted by X [m2 / g], the surface treatment is carried out at a phosphorus quantity corresponding to 0.11X -11.0X parts by mass relative to 100 parts by mass of the aluminum nitride-based filler.

Description

Aluminum nitride filler and resin composition

[0001] The present invention relates to an aluminum nitride filler and a resin composition.

[0002] Aluminum nitride is known as a material with excellent thermal conductivity, electrical insulation, and the like. Taking advantage of these properties, aluminum nitride is used in a variety of applications. In particular, it has attracted attention as a thermally conductive filler for enhancing the thermal conductivity of resin compositions. For example, with regard to electronic components (resin products) made of resin, such as semiconductor substrates, measures to deal with heat generated by electronic components (heat dissipation means) are becoming more important than ever as electronic devices become smaller and more highly integrated. For this reason, various techniques have been proposed for incorporating aluminum nitride as a filler into resins.

[0003] However, aluminum nitride is inherently reactive with water. It is known that aluminum nitride reacts with water, causing hydrolysis and generating ammonia as follows: AlN+3H ２ O → Al(OH) ３ +NH ３ ↑

[0004] Aluminum nitride contained in resins can also react with moisture in the air or in the resin, potentially degrading the quality of the resin product.

[0005] For this reason, attempts have been made to solve the above-mentioned problems by surface-treating the aluminum nitride particle surfaces.

[0006] For example, an aluminum nitride-based powder has been proposed (Patent Document 1), which is a powder consisting of composite particles in which a coating layer is formed on the surface of aluminum nitride particles, in which (1) the coating layer contains Si, O, H, and an alkyl group, and (2) the amount of organic carbon in the powder is 0.02 to 1.0 wt %.

[0007] Further, for example, a filler in which an oxide film is formed on the surface of aluminum nitride particles, the filler has an actual measured value of a specific surface area measured by the BET method of A (m ２ / g), and the specific surface area calculated when the shape is assumed to be spherical is B (m２ / g), an aluminum nitride filler having an [A / B] value of 1 to 29.9 has been proposed (Patent Document 2).

[0008] However, these techniques have not yet yielded fibrous aluminum nitride fillers with satisfactory water resistance, etc., in order to further improve thermal conductivity, and there is room for further improvement in this regard.

[0009] JP 2006-290667 A JP 2021-127288 A

[0010] An object of the present invention is to provide an aluminum nitride filler having excellent water resistance and thermal conductivity, and to provide a resin composition having excellent water resistance and thermal conductivity.

[0011] The above object is achieved by the present invention as set forth in the following (1) to (6): (1) An aluminum nitride filler comprising fibrous aluminum nitride particles having an oxide coating formed on the surface thereof, the oxide coating of the aluminum nitride particles having been subjected to a surface treatment with a phosphorus-based compound, wherein the amount of surface oxygen measured by the NDIR method is 2.0% or more and 30.0% or less, and the specific surface area of ​​the aluminum nitride particles measured by the BET method is X [m ２ / g], the aluminum nitride filler is surface-treated with a phosphorus amount of 0.03X parts by mass or more and 10X parts by mass or less per 100 parts by mass of the aluminum nitride filler.

[0012] (2) The aluminum nitride filler according to (1), wherein the phosphorus compound is an inorganic phosphorus compound or an organic phosphorus compound.

[0013] (3) A specific surface area measured by the BET method is 1.0 m ２ / g or more 4.0m ２ / g or less.

[0014] (4) The aluminum nitride filler according to any one of (1) to (3), wherein the aspect ratio of the aluminum nitride particles is 2 or more and 200 or less.

[0015] (5) A resin composition containing the aluminum nitride filler according to any one of (1) to (4) above and a resin.

[0016] (6) The resin composition according to (5) above, wherein the content of the aluminum nitride filler is 5% by volume or more and 60% by volume or less.

[0017] According to the present invention, it is possible to provide an aluminum nitride filler having excellent water resistance and thermal conductivity, and also to provide a resin composition having excellent water resistance and thermal conductivity.

[0018] FIG. 1 is a table showing the composition of the aluminum nitride filler in each example and each comparative example, as well as the evaluation results.

[0019] Preferred embodiments of the present invention will be described in detail below. [1] Aluminum nitride filler First, the aluminum nitride filler of the present invention will be described.

[0020] The aluminum nitride filler of the present invention comprises fibrous aluminum nitride particles having an oxide coating formed on the surface thereof, and the oxide coating of the aluminum nitride particles is surface-treated with a phosphorus-based compound. The aluminum nitride filler of the present invention has a surface oxygen content measured by the NDIR method of 1.98% or more and 9.40% or less, and a specific surface area of ​​the aluminum nitride particles measured by the BET method of X [m ２ / g], the surface treatment is carried out with a phosphorus amount of 0.11X parts by mass or more and 11.0X parts by mass or less per 100 parts by mass of the aluminum nitride filler.

[0021] By satisfying these conditions, it is possible to provide an aluminum nitride filler having excellent water resistance and thermal conductivity.

[0022] More specifically, the aluminum nitride filler contains fibrous aluminum nitride particles having an oxide coating formed on the surface thereof, and the oxide coating of the aluminum nitride particles is surface-treated with a phosphorus-based compound, thereby imparting excellent water resistance to the aluminum nitride filler.

[0023] In particular, when the surface oxygen amount of the aluminum nitride-based filler (surface oxygen amount measured by the NDIR method) is within the above range, an appropriate amount of phosphorus can be stably attached to the surfaces of the aluminum nitride particles that make up the aluminum nitride-based filler, and the aluminum nitride-based filler can have excellent water resistance and thermal conductivity.

[0024] Furthermore, by ensuring that the amount of phosphorus relative to the aluminum nitride particles in the aluminum nitride filler (amount of surface treatment with phosphorus) is within the above range, the water resistance and thermal conductivity of the aluminum nitride filler can be made excellent.

[0025] Furthermore, since the aluminum nitride particles are fibrous, the aluminum nitride filler is also fibrous, and a heat transfer path can be suitably secured even with few contact points between the aluminum nitride fillers. Furthermore, by reducing the number of contact points between the aluminum nitride fillers, the thermal resistance can be reduced. As a result, the thermal conductivity of the aluminum nitride filler can be improved.

[0026] On the other hand, if the above conditions are not met, the above excellent effects cannot be obtained.

[0027] For example, if the surface oxygen content of the aluminum nitride filler is less than the lower limit, it becomes difficult to attach a sufficient amount of phosphorus to the surface of the aluminum nitride particles, and the water resistance of the aluminum nitride filler cannot be sufficiently excellent. On the other hand, if the surface oxygen content of the aluminum nitride filler exceeds the upper limit, the thermal conductivity of the aluminum nitride filler decreases.

[0028] Furthermore, for example, if the amount of phosphorus relative to the aluminum nitride particles in the aluminum nitride filler (amount of surface treatment with phosphorus) is less than the lower limit, the water resistance of the aluminum nitride filler cannot be made sufficiently excellent. On the other hand, if the amount of phosphorus relative to the aluminum nitride particles in the aluminum nitride filler (amount of surface treatment with phosphorus) exceeds the upper limit, the thermal conductivity of the aluminum nitride filler will decrease.

[0029] In the present invention, the surface oxygen content of the aluminum nitride filler refers to the oxygen content on the surface of the aluminum nitride filler, and is a value including the oxygen content in the oxide film and the oxygen content in the surface treatment region with a phosphorus-based compound. Furthermore, the oxygen content of the oxide film can usually be calculated by subtracting the oxygen content of the phosphorus-based compound used in the surface treatment from the surface oxygen content (the surface oxygen content of the aluminum nitride filler), and the oxygen content of the phosphorus-based compound can be calculated by subtracting the oxygen content of the oxide film of the aluminum nitride particle from the surface oxygen content.

[0030] In the following description, the aluminum nitride filler of the present invention may be simply referred to as "filler".

[0031] [1-1] Aluminum Nitride Particles The aluminum nitride particles are the core particles of the aluminum nitride filler of the present invention, and have an oxide coating formed on the surface thereof.

[0032] Generally, the proportion of the surface treatment region of the phosphorus-based compound in the aluminum nitride filler is sufficiently small compared to the proportion of the aluminum nitride particles, and the aluminum nitride particles have the same shape and size as the corresponding aluminum nitride filler. In other words, the aluminum nitride particles are also fibrous.

[0033] The aspect ratio of the aluminum nitride particles, i.e., the value of L1 / L2, where L1 [μm] is the length of the aluminum nitride particle in the major axis direction and L2 [μm] is the length of the aluminum nitride particle in the minor axis direction perpendicular to the major axis, is preferably 2 or more and 200 or less, more preferably 3 or more and 180 or less, and even more preferably 5 or more and 150 or less.

[0034] This makes it possible to make the above-mentioned effects more pronounced. Furthermore, when a resin composition is prepared using the aluminum nitride filler, the resin composition can have favorable flowability and moldability.

[0035] In this specification, the term "aspect ratio" refers to the arithmetic mean value of the aspect ratios of 30 randomly selected target particles.

[0036] The aluminum nitride filler is also preferred because it satisfies the same condition as the aspect ratio of the aluminum nitride particles, thereby providing the same effects as those described above.

[0037] The average particle size of the aluminum nitride particles is not particularly limited, but D50, measured by a volume distribution analyzer using a laser diffraction particle size distribution analyzer, is preferably 0.1 μm or more and 500 μm or less, more preferably 1 μm or more and 100 μm or less, and even more preferably 1 μm or more and 50 μm or less.

[0038] This can improve the water resistance of the aluminum nitride filler, and can also improve the non-catalytic toxicity and filling properties when the aluminum nitride filler is dispersed in a resin to prepare a resin composition.

[0039] The aluminum nitride filler is also preferable because it satisfies the same conditions as the average particle size of the aluminum nitride particles, thereby providing the same effects as those described above.

[0040] [1-1-1] Oxide Coating An oxide coating is formed on the surface of the aluminum nitride particles.

[0041] The formation of the oxide film can impart excellent water resistance, non-catalytic toxicity, packing properties, and the like to the aluminum nitride particles.

[0042] The oxide coating may be a surface layer that covers at least a portion of the surface of the aluminum nitride particles, but it is preferable that the oxide coating covers substantially the entire surface of the aluminum nitride particles.

[0043] As the oxide, various metal or nonmetal oxides can be used. Examples include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, and cerium oxide. One or more of these may be contained. Among the above oxides, oxides obtained by a sol-gel method are preferably used.

[0044] The amount of the oxide film formed (coating amount) is preferably 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the aluminum nitride particles.

[0045] This allows the aluminum nitride filler to have better water resistance and thermal conductivity.

[0046] The thickness of the surface layer is not particularly limited, but may be 1 nm or more and 200 nm or less.

[0047] This allows the aluminum nitride filler to have better water resistance and thermal conductivity.

[0048] The surface oxygen content of the aluminum nitride particles is preferably 0.5% or more and 3.0% or less.

[0049] This allows the phosphorus-based compound to adhere more favorably to the oxide film during surface treatment with the phosphorus-based compound, thereby improving the water resistance and thermal conductivity of the aluminum nitride-based filler.

[0050] The surface oxygen content of aluminum nitride particles can be determined, for example, by measuring aluminum nitride particles used as a raw material for the aluminum nitride filler by the above-mentioned NDIR method.

[0051] The BET specific surface area of ​​the aluminum nitride particles is 0.5 m ２ / g or more 4.0m ２ / g or less is preferred.

[0052] This allows a sufficient amount of phosphorus to be attached to the surface during the surface treatment with a phosphorus-based compound, thereby making it possible to improve the water resistance and thermal conductivity of the aluminum nitride-based filler.

[0053] [1-2] Surface Treatment with Phosphorus-Based Compound In the aluminum nitride filler of the present invention, the oxide coating of the aluminum nitride particles is surface-treated with a phosphorus-based compound.

[0054] The phosphorus compound is not particularly limited, but it is preferable to use an inorganic phosphorus compound or an organic phosphorus compound.

[0055] This causes the OH groups present in the oxide coating of the aluminum nitride particles to react with the phosphoric acid, forming a chemical bond, allowing the phosphorus-based compound to adhere firmly to the aluminum nitride particles, thereby imparting superior water resistance to the aluminum nitride particles.

[0056] Examples of inorganic phosphate compounds include phosphoric acid, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, aluminum phosphate, and sodium phosphate.

[0057] The organic phosphoric acid compound may be, for example, a compound represented by the general formula (RO): ２ P(O)OH or ROP(O)(OH) ２ (wherein R is an alkyl group, an alkenyl group, or an aryl group having from 1 to 18 carbon atoms), such as methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, 2-ethylhexyl acid phosphate, lauryl acid phosphate, palmityl acid phosphate, stearyl acid phosphate, oleyl acid phosphate, phenyl acid phosphate, and nonylphenyl acid phosphate.

[0058] Other examples of organic phosphoric acid compounds include mono- or dialkyl, alkenyl, or aryl esters of pyrophosphoric acid or polyphosphoric acid, such as di-2-ethylhexyl pyrophosphate; phosphonic acids and esters thereof, such as methylene phosphonic acid, aminomethylene phosphonic acid, t-butylnitrilobismethylene phosphonic acid, n-butylnitrilobismethylene phosphonic acid, nitrilotrismethylene phosphonic acid, ethylenediaminetetramethylene phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, butyl hydrogen phosphite, 2-ethylhexyl hydrogen phosphite, lauryl hydrogen phosphite, dibutyl hydroxymethyl phosphonate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, tricresyl phosphate, and triphenyl phosphate.

[0059] Among these, it is preferable to use at least one selected from the group consisting of phosphoric acid, orthophosphoric acid, polyphosphoric acid, phosphorous acid, ammonium phosphate, ammonium dihydrogen phosphate, acidic phosphate esters, and salts thereof.

[0060] [1-3] Other conditions The BET specific surface area of ​​the aluminum nitride filler of the present invention is 1.0 m ２ / g or more 4.0m ２ / g or less is preferred.

[0061] As a result, when a resin composition is prepared using the aluminum nitride-based filler of the present invention, the adhesion between the filler and the resin is improved, and the strength and thermal conductivity of a molded article produced using the resin composition can be improved.

[0062] [2] Method for Producing Aluminum Nitride Filler Next, a method for producing an aluminum nitride filler will be described.

[0063] The aluminum nitride filler of the present invention can be suitably produced, for example, by a method including a preparation step of preparing fibrous aluminum nitride particles having an oxide coating formed on the surface thereof, and a surface treatment step of performing a surface treatment on the aluminum nitride particles using a phosphorus-based compound.

[0064] [2-1] Preparation Step In the preparation step, fibrous aluminum nitride particles having an oxide coating formed on the surface thereof are prepared.

[0065] The aluminum nitride particles may contain other components (e.g., Al) within the range that does not impair the effects of the present invention. ２ O ３ etc.) may also be included.

[0066] The aluminum nitride particles may be produced by any method, and for example, aluminum nitride particles obtained by a direct nitriding method, aluminum nitride particles obtained by a reduction method, etc. As a method for forming an oxide coating on the surface of the aluminum nitride particles, it is preferable to use a sol-gel method as described below.

[0067] That is, fibrous aluminum nitride particles having an oxide coating formed on the surface thereof can be suitably produced by a method including: (a) a first step of preparing a mixed solution by adding an alkoxide compound to a dispersion in which aluminum nitride powder is dispersed in a solvent; (b) a second step of hydrolyzing the alkoxide compound by adding an acid catalyst to the mixed solution; (c) a third step of adding a base catalyst to the mixed solution after hydrolysis; and (d) a fourth step of drying the obtained reaction product.

[0068] Specifically, for example, aluminum nitride particles having an oxide coating formed on the surface can be produced by the method described in JP-A-2021-127288.

[0069] Commercially available aluminum nitride particles may also be used, such as "Thermalnite" manufactured by U-MAP.

[0070] [2-2] Surface Treatment Step In the surface treatment step, the aluminum nitride particles are surface-treated using a phosphorus-based compound.

[0071] Specifically, for example, by mixing a dispersion liquid in which aluminum nitride particles are dispersed in a solvent with a phosphorus-based compound, the phosphorus-based compound can be attached to the surfaces of the aluminum nitride particles.

[0072] The solvent used for the dispersion is not particularly limited, but is preferably an aqueous solvent, and at least one of water, a water-soluble organic solvent, and a mixture thereof can be suitably used as the aqueous solvent.

[0073] Specific examples of the water-soluble organic solvent include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, t-butyl alcohol, n-butyl alcohol, and isobutyl alcohol; cellosolves such as ethyl cellosolve and butyl cellosolve; ethers such as propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, and propylene glycol monopropyl ether; and ketones such as acetone.

[0074] The content of aluminum nitride particles in the dispersion is not particularly limited, but is preferably 10% by mass or more and 60% by mass or less.

[0075] The phosphorus-based compound may be mixed directly with a dispersion of aluminum nitride particles dispersed in a solvent, or may be mixed in the form of an aqueous solution, for example. When an aqueous solution of the phosphorus-based compound is used, the concentration of the phosphorus-based compound in the aqueous solution may be, for example, 0.05 g / L or more and 100 g / L or less.

[0076] When adding a phosphorus-based compound to a dispersion liquid in which aluminum nitride particles are dispersed in a solvent, the method of adding the phosphorus-based compound is not particularly limited, and may be any of a method of adding the entire amount at once, a method of adding the compound in two or more portions, a dropwise method, etc. When adding the phosphorus-based compound, it is preferable to add the phosphorus-based compound while stirring the dispersion liquid.

[0077] The amount of phosphorus-based compound used is appropriately determined depending on the type of phosphorus-based compound, etc., but the specific surface area of ​​aluminum nitride particles measured by the BET method is X [m ２ / g], the phosphorus content is determined so that the ratio is 0.11X parts by mass or more and 11.0X parts by mass or less per 100 parts by mass of the aluminum nitride filler.

[0078] The preparation and stirring of the dispersion can be carried out using a known mixing device, stirring device, etc. Examples of the mixing device and stirring device include a kneader, a kneading machine, a rotary vessel stirrer, a stirred reaction tank, a V-type stirrer, a double cone stirrer, a screw mixer, a sigma mixer, a flash mixer, an airflow stirrer, a ball mill, and an edge runner.

[0079] The treatment temperature is usually set to a temperature equal to or lower than the boiling point of the solvent used, but is not particularly limited thereto. The stirring time is not particularly limited, but can be set to a temperature of 30 minutes to 4 hours.

[0080] [2-3] Drying Step In addition to the steps described above, the method for producing an aluminum nitride filler may further include a drying step of drying the resulting reaction product.

[0081] In the surface treatment step, the reaction product is generated as a solid content in the dispersion, and if necessary, the solid content may be separated and recovered by solid-liquid separation, and then the reaction product may be dried. As a method for solid-liquid separation, a known method such as filtration or centrifugation may be used.

[0082] The drying temperature is not particularly limited, but is preferably 50° C. or higher and 150° C. or lower. The drying time varies depending on the drying temperature, but is preferably 5 minutes or longer. In addition to the above-mentioned thermal drying, the solvent can also be removed by vacuum decompression.

[0083] After drying, a heat treatment may be carried out as necessary. The treatment temperature in the heat treatment is not particularly limited, but is preferably 200° C. or higher and 800° C. or lower, and more preferably 300° C. or higher and 500° C. or lower. The treatment atmosphere is not particularly limited, and can be, for example, air.

[0084] [3] Uses of Aluminum Nitride Filler Next, uses of the aluminum nitride filler of the present invention will be described.

[0085] The aluminum nitride filler of the present invention can be used as various fillers (filling materials), and is particularly suitable for use as a filler to be dispersed in a resin.

[0086] The aluminum nitride filler of the present invention has particularly excellent thermal conductivity because it uses aluminum nitride as the core particle, and therefore can be suitably used as a filler for imparting high thermal conductivity (heat dissipation) to a resin composition.

[0087] Furthermore, the aluminum nitride filler of the present invention contains aluminum nitride particles having an oxide coating formed on the surface thereof, and satisfies predetermined conditions for the amounts of oxygen and phosphorus on the surface thereof, and therefore has excellent water resistance. Therefore, even when the aluminum nitride filler of the present invention is dispersed in a resin, deterioration of the resin quality due to the reaction of aluminum nitride with moisture is suitably suppressed.

[0088] For the reasons mentioned above, the aluminum nitride filler of the present invention can be particularly suitably used as a filler for resin compositions.

[0089] [4] Resin Composition Next, the resin composition of the present invention will be described.

[0090] The resin composition of the present invention contains the aluminum nitride filler described above and a resin.

[0091] This makes it possible to provide a resin composition having excellent water resistance and thermal conductivity. Furthermore, the reaction of the aluminum nitride filler with moisture in the atmosphere or the resin is suitably suppressed, and high quality can be suitably maintained for a long period of time.

[0092] By dispersing fibrous aluminum nitride fillers in a resin so that they are oriented in random directions along their length, the contact density per unit volume between the aluminum nitride fillers can be increased, and even if the amount dispersed is small, high thermal conductivity can be imparted to the resin composition.

[0093] The above-mentioned effects are exerted not only in the resin composition but also in the molded article produced using the resin composition.

[0094] The resin may be any of various thermoplastic resins, thermosetting resins, etc. More specifically, examples of the resin include silicone resin, acrylic resin, epoxy resin, polyester resin, polyurethane resin, polyvinyl acetate resin, nitrocellulose resin, and fluororesin.

[0095] In particular, when a resin (such as a silicone resin) that is polymerized and hardened by a catalyst in which nitrogen in aluminum nitride acts as a catalyst poison is used, the effect of the present invention is more pronounced.

[0096] The method for mixing the aluminum nitride-based filler with the resin is not particularly limited, and various methods can be used, such as (a) a method of kneading a filler with a molten resin, or (b) a method of adding a filler to a resin powder and then melt-kneading the mixture.

[0097] The content (volume ratio) of the resin in the resin composition is preferably 5% by volume or more and 60% by volume or less, and more preferably 10% by volume or more and 50% by volume or less.

[0098] This allows the resin composition to have sufficiently excellent fluidity, and the molded article produced using the resin composition to have better water resistance and thermal conductivity, and also allows the molded article produced using the resin composition to have more suitable mechanical properties such as strength and flexibility.

[0099] The content of the aluminum nitride filler in the resin composition can be 5 parts by mass or more and 900 parts by mass or less per 100 parts by mass of the resin.

[0100] The content (volume ratio) of the aluminum nitride filler in the resin composition is preferably 5% by volume or more and 60% by volume or less, and more preferably 10% by volume or more and 50% by volume or less.

[0101] This allows the resin composition to have sufficiently excellent fluidity, and the molded article produced using the resin composition to have better water resistance and thermal conductivity, and also allows the molded article produced using the resin composition to have more suitable mechanical properties such as strength and flexibility.

[0102] The resin composition of the present invention may further contain components other than the aluminum nitride filler and resin described above. Hereinafter, such components will be referred to as "other components."

[0103] Examples of other components include fillers other than the aluminum nitride filler of the present invention, surfactants, curing agents, crosslinking agents, ultraviolet absorbers, static eliminators, thickeners, colorants, and corrosion inhibitors.

[0104] The content of other components in the resin composition of the present invention is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0105] [5] Molded Article Next, the molded article according to the present invention will be described.

[0106] The molded article according to the present invention contains the aluminum nitride filler according to the present invention. In particular, the molded article according to the present invention is preferably produced using the resin composition according to the present invention.

[0107] When the molded article according to the present invention is produced using the resin composition of the present invention, the molded article preferably has the same composition as the above-mentioned resin composition, thereby obtaining the same effects as those described above.

[0108] The molded article according to the present invention may be any type, but can be suitably applied to, for example, electronic parts, automobile parts, and the like, which require high heat dissipation properties and water resistance.

[0109] The method for molding a molded article using a resin composition is not particularly limited, but known methods such as pressure molding and injection molding can be used depending on the type of resin used.

[0110] The bending stress of the molded article is preferably 0.2 MPa or more, and more preferably 0.4 MPa or more, so that the molded article can be suitably used as various parts.

[0111] In this specification, the bending stress of the molded body refers to a value measured by a three-point bending test using a three-point bending test jig in accordance with the method described in JIS K7171:2016.

[0112] The thermal conductivity of the molded article at 25° C. is preferably 1.0 W / (m·K) or more, and more preferably 4.0 W / (m·K) or more.

[0113] This makes it suitable for use in molded articles that require higher thermal conductivity (heat dissipation).

[0114] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0115] For example, the aluminum nitride filler of the present invention is not limited to those produced by the production method described above. More specifically, the aluminum nitride filler of the present invention may be produced by a method having other steps in addition to the steps described above.

[0116] The present invention will be described in more detail below with reference to specific examples, but the present invention is not limited to these examples. In the following description, treatments for which no temperature conditions are specified were performed at room temperature, specifically 25°C. Furthermore, various measurement conditions for which no temperature conditions are specified are values ​​at room temperature, specifically 25°C.

[0117] [6] Production of Aluminum Nitride Filler Example 1 First, Thermalnite manufactured by U-MAP was prepared as fibrous aluminum nitride particles having an oxide coating formed on the surface.

[0118] The aluminum nitride particles have a BET specific surface area of ​​2.10 g / m ２ and the aspect ratio was 7.0.

[0119] 1500 g of isopropyl alcohol was placed in a 3 L container with a lid. While the isopropyl alcohol was being stirred, 20.0 g of the aluminum nitride particles were added and thoroughly dispersed.

[0120] To this dispersion, 1.2 g of a 10% by mass aqueous solution of phosphoric acid was slowly added. After stirring for 30 minutes, fine powder was removed using a filter and solid-liquid separation was performed. The resulting solid was dried in a vacuum at 70°C to obtain an aluminum nitride filler surface-treated with phosphoric acid.

[0121] (Examples 2 to 6) Aluminum nitride-based fillers surface-treated with phosphoric acid were produced in the same manner as in Example 1, except that the conditions of the fibrous aluminum nitride particles used as raw materials and the amount of phosphoric acid used were changed.

[0122] (Comparative Example 1) The aluminum nitride particles were not surface-treated with a phosphorus-based compound, and were used as they were as the aluminum nitride filler of Comparative Example 1. (Comparative Examples 2 to 4) Aluminum nitride fillers surface-treated with phosphoric acid were produced in the same manner as in Example 1, except that the conditions of the fibrous aluminum nitride particles used as a raw material and the amount of phosphoric acid used were changed.

[0123] [7] Evaluation The aluminum nitride fillers of the above examples and comparative examples were evaluated as follows.

[0124] [7-1] Surface Oxygen Content The surface oxygen content was measured by pyrolysis in an inert gas and measuring infrared absorption using an oxygen / nitrogen analyzer (EMGA-2800) manufactured by Horiba, Ltd.

[0125] [7-2] BET Specific Surface Area The BET specific surface area was measured using a fully automatic specific surface area measuring device (Macsorb (registered trademark) HM Model-1201) manufactured by Mountech Co., Ltd.

[0126] [7-3] Evaluation of Water Resistance The aluminum nitride fillers of each of the Examples and Comparative Examples were exposed to a high-temperature, high-humidity environment of 85°C and 85 RH% for 16 hours using an environmental tester (ESPEC SH242) manufactured by ESPEC Corporation.

[0127] The surface oxygen content was measured before and after exposure to a high-temperature, high-humidity environment, and the rate of change was calculated using the following formula: Rate of change (%) = {(surface oxygen content after exposure - surface oxygen content before exposure) / surface oxygen content before exposure} x 100

[0128] The smaller the rate of change, the better the water resistance.

[0129] [7-4] Evaluation of Thermal Conductivity Resin compositions were prepared by dispersing the aluminum nitride fillers of each of the Examples and Comparative Examples in a silicone resin. The content of the aluminum nitride filler in the resin composition was 5% by volume, and the content of the resin in the resin composition was 95% by volume. The thermal conductivity of the silicone resin at 25°C was 0.2 W / (m·K).

[0130] The resulting resin composition was poured into a disk-shaped silicone mold having a diameter of 25 mm and a thickness of 5 mm, molded, and treated at 150° C. for 60 minutes to obtain a molded body as a sample for measuring thermal conductivity.

[0131] The thermal conductivity of each of the obtained samples for thermal conductivity measurement was measured by a non-steady state method using a thermal conductivity measuring device (TCi) manufactured by C-THERM.

[0132] The results of these evaluations are shown together with the configuration of the aluminum nitride-based fillers of the respective Examples and Comparative Examples in Figure 1. In Figure 1, the value of "phosphorus amount [parts by mass]" indicates the ratio of phosphorus to 100 parts by mass of aluminum nitride, and the column "phosphorus amount (relationship with specific surface area) [parts by mass]" indicates the specific surface area of ​​the aluminum nitride particles measured by the BET method as X [m ２ / g], the amount of phosphorus used in the surface treatment relative to 100 parts by mass of the aluminum nitride filler is shown in a form including x.

[0133] As is clear from Figure 1, the present invention provided excellent water resistance and thermal conductivity, whereas the comparative example did not provide satisfactory results.

[0134] Furthermore, molded bodies were produced using the aluminum nitride fillers of the above examples in the same manner as in [7-4] above, except that the content of the aluminum nitride filler was changed in various ways within the range of 5 mass % or more and 60 mass % or less, and the bending stress of these molded bodies was measured. Excellent effects were obtained in all cases.

[0135] According to the present invention, it is possible to provide an aluminum nitride filler having excellent water resistance and thermal conductivity, and to provide a resin composition having excellent water resistance and thermal conductivity. Therefore, the present invention has industrial applicability.

Claims

1. A fibrous aluminum nitride filler containing fibrous aluminum nitride particles having an oxide film formed on the surface, and having a surface treatment with a phosphorus compound on the oxide film of the aluminum nitride particles, wherein the surface oxygen amount measured by the NDIR method is 1.98% or more and 9.40% or less, and when the specific surface area of the aluminum nitride particles measured by the BET method is X [m ２ / g], the surface treatment is performed with a phosphorus amount in a ratio of 0.11X parts by mass or more and 11.0X parts by mass or less with respect to 100 parts by mass of the aluminum nitride-based filler.

2. The aluminum nitride-based filler according to claim 1, wherein the phosphorus compound is an inorganic phosphoric acid compound or an organic phosphoric acid compound.

3. The specific surface area measured by the BET method is 1.0 m ２ / g or more and 4.0 m ２ / g or less, and the aluminum nitride-based filler according to claim 1 or 2.

4. The aluminum nitride-based filler according to claim 1 or 2, wherein the aspect ratio of the aluminum nitride particles is 2 or more and 200 or less.

5. A resin composition comprising the aluminum nitride-based filler according to claim 1 or 2 and a resin.

6. The resin composition according to claim 5, wherein the content of the aluminum nitride-based filler is 5% by volume or more and 60% by volume or less.